Language Design: Use 'ident: Type' not 'Type ident'

Language design affects how good autocomplete and error messages can be. That is hugely important.

Having said that, this article doesn’t advocate “ident: Type”, it advocates ”marker ident: Type”.

That marker is essential for ease of parsing and thus for autocomplete (it won’t try to autocomplete the ‘ident’ part by looking at variables in scope or function names, for example) and error messages (it could signal when name shadowing occurs, for example)

Many languages allow you to elide the type, which is another nice thing about the type following the identifier.

In Scala, in particular, types are not the assigned type like in C (where they also serve as the storage specification) -- they are assertions, that the compiler will check are compatible with the code.

So `val x: int = "hello"` is no good and the compiler can cut it short right there; this is especially useful as call-site documentation.

Interestingly, I find ident: Type significantly more difficult to read. Having the type information helps me contextualize what I'm about to read -- it narrows the mental search space I need to explore when parsing the name.

For example, knowing something is a float, double, int, or string can make an ident named "releaseTime" mean different things.

I also find that whitespace is more consistent when using Type ident, you get rivers where the spaces all line up, so all the type declarations AND ident declarations align. Whereas with ident: Type, I find it much more difficult because of the variable length of identifiers. (Yes, one could fix this by using tabs, but if idents vary in length by more than one tab stop, it becomes difficult to read horizontally.)

I’m surprised this didn’t touch on the IDE autocomplete suggesting variable names. In Java you would have something like `LocationBuilder locationBuilder` which makes users just tab complete the variable name to quickly have access to a variable. The argument in this article was about names being prioritized and I think forcing no auto completion on a variable name would force the developer to be slightly more descriptive than the variablized string of a class name

I replied elsewhere that I found the opposite to be true. So I suspect that different people will find different styles to be easier/harder to parse.

> the harder it is for a computer to parse, the harder it is for a human to parse,

I don't think this is true -- assembly (or bytecode) is very easy for the computer to parse, but much, much harder for humans to parse. English is much easier for humans to parse, but pretty difficult for computers to parse.